My go-to “walkaround” settings on my mirrorless Sony A6000 and RX-10 are:
- Aperture priority
“Floating” (auto) ISO, sometimes capped, more often not (I can control most noise and anyway some does not bother me that much)
Auto WB (I am always shooting 100% raw)
Continuous autofocus
Lock-on autofocus
Burst mode, usually mid-range (about 5 fps, sometimes slow, 2 fps, that allows me to make one exposure and stop)
Walk-around zoom, Sony E PZ 18-105mm F4 G OSS (holds f/4.0 throughout, equivalent 27 mm to 157 mm, pretty much perfect mid-range for anything)
(The RX-10 has a 24 - 200 equivalent zoom on a 1” sensor. I’m using it very little now, preferring the superior performance of the A6000 with its APS-C half-frame sensor.)
So here’s what I discovered: When in my favorite walkaround settings, the camera AUTOMATICALLY selects a shutter speed roughly double the actual focal length. They do it with incredible consistency, especially since I allow the ISO to “float.” At 18 mm for example the Sonys will almost always select a shutter around 1/40 sec at any aperture since they can also adjust the ISO for the conditions, bright or available dark. Zoom out to 35 mm and the cameras will instantly select a shutter around 1/70 - 1/80 second. Zoom to 105 and glance at the shutter, it will be 1/200. On my A6000 with the 18 - 105 f/4 it matters not where I set the aperture, the camera will consistently double the shutter based on the focal length unless I’m in near darkness (and I do that because I am quite gibbering mad). For a total sharp freak this is utterly AWESOMESAUCE!
The thing that makes this wonderful from my viewpoint is that I can, for the most part, concentrate on composition and action and not worry at all if I am getting well exposed, reasonably sharp pictures. I know how and when to use manual, and I’ve used shutter priority sometimes when I thought it better, but this discovery means that I really don’t need shutter priority -- the camera will handle it for me and having control of DOF is far preferable. All I need do is select an aperture consistent with the DOF I want, zoom or not, and wherever the lens is set the camera will double the focal length for the shutter speed. I think that is SO COOL!
Examples:
Grampa's Personal Favorite (Centennial Mall Fountain) by Charles Haacker, on Flickr
At ƒ/5.0 and 80.0 mm the camera selected 1/1000 at ISO 100 because we are in nice bright sun. Note the freezing of the water. The camera nailed the focus on her face. She is running around in a fountain in street clothes getting totally sopped.
The heat index that day was 104. 
This one is inside the Children's Museum, the first time she has been able to weigh herself in the bucket as she is now over 30 pounds.
33 Pounds Soaking Wet! Really! by Charles Haacker, on Flickr
Here, shooting at ƒ/5.6 and zoomed back to 27.0 mm equivalent to 40 mm full frame), the camera selected 1/60 second at ISO 8000. In these cases I apply more noise control, but my intent is always just to get the picture! Sure, I could do all this in manual... And miss a lot of cute shots.
I also volunteer to do occasional event photography. I own but rarely use a flash unit because I hate the look. I'm very much an available dark nut and infinitely prefer to battle noise than lose the look of the natural light. I'm pretty chuffed to have discovered this convenience.
